1. Field of the Invention
The present invention relates generally to apparatus for effecting programmed material consolidation techniques, such as stereolithography, and, more particularly, to apparatus that are configured to fabricate features on semiconductor devices and related components. The present invention also relates to programmed material consolidation methods that include use of such apparatus.
2. Background of Related Art
Over the past decade or so, a manufacturing technique which has become known as “stereolithography” and which is also known as “layered manufacturing” has evolved to a degree where it is employed in many industries.
Basically, stereolithography, as conventionally practiced, involves utilizing a computer, typically under control of three-dimensional (3-D) computer-aided design (CAD) software, to generate a 3-D mathematical simulation or model of an object to be fabricated. The computer mathematically separates or “slices” the simulation or model into a large number of relatively thin, parallel, usually vertically superimposed layers. Each layer has defined boundaries and other features that correspond to a substantially planar section of the simulation or model and, thus, of the actual object to be fabricated. A complete assembly or stack of all of the layers defines the entire simulation or model. A simulation or model which has been manipulated in this manner is typically stored and, thus, embodied as a CAD computer file. The simulation or model is then employed to fabricate an actual, physical object by building the object, layer by superimposed layer. Surface resolution of the fabricated object is, in part, dependent upon the thickness of the layers.
A wide variety of approaches to stereolithography by different companies has resulted in techniques for fabricating objects from various types of materials. Regardless of the material employed to fabricate an object, stereolithographic techniques usually involve disposition of a layer of unconsolidated or unfixed material corresponding to each layer of the simulation or model. Next, the material of a layer is selectively consolidated or fixed to at least a partially consolidated, partially fixed, or semisolid state in those areas of a given layer that correspond to solid areas of the corresponding section of the simulation or model. Also, while the material of a layer is being consolidated or fixed, that layer may be bonded to a lower layer of the object which is being fabricated.
The unconsolidated material employed to build an object may be supplied in particulate or liquid form. The material may itself be consolidated or fixed. Alternatively, when the unconsolidated material comprises particles, a separate binder material mixed therein or coating the particles may facilitate bonding of the particles to one another, as well as to the particles of a previously formed layer.
Surface resolution of the features of a fabricated object depends, at least in part, upon the material being used. For example, when particulate materials are employed, resolution of object surfaces is highly dependent upon particle size, whereas when a liquid is employed, surface resolution is highly dependent upon the minimum surface area of the liquid which can be consolidated or fixed and the minimum thickness of a material layer that can be generated. Of course, in either case, resolution and accuracy of the features of an object being produced from the simulation or model are also dependent upon the ability of the apparatus used to consolidate or fix the material to precisely track the mathematical instructions indicating solid areas and boundaries for each layer of material.
Toward that end, and depending upon the type and form of material to be fixed, stereolithographic fabrication processes have employed various fixation approaches. For example, particles have been selectively consolidated by particle bombardment (e.g., with electron beams), disposition of a binder or other fixative in a manner similar to ink-jet printing techniques, and focused irradiation using heat or specific wavelength ranges. In some instances, thin, preformed sheets of material may be superimposed to build an object, each sheet being fixed to a next-lower sheet and unwanted portions of each sheet removed, a stack of such sheets defining the completed object.
Early on in its development, stereolithography was used to rapidly fabricate prototypes of objects from CAD files. Prototypes of objects might be built to verify the accuracy of the CAD file defining the object (e.g., an object or negative of a mold to be machined) and to detect any design deficiencies and possible fabrication problems before a design was committed to large-scale production. Stereolithographic techniques have also been used in the fabrication of molds. Using stereolithographic techniques, either male or female forms on which mold material might be disposed could be rapidly generated.
In more recent years, stereolithography has been employed to develop and refine object designs in relatively inexpensive materials. Stereolithography has also been used to fabricate small quantities of objects for which the cost of conventional fabrication techniques is prohibitive, such as in the case of plastic objects that have conventionally been formed by injection molding techniques. It is also known to employ stereolithography in the custom fabrication of products generally built in small quantities or where a product design is rendered only once. Finally, it has been appreciated in some industries that stereolithography provides a capability to fabricate products, such as those including closed interior chambers or convoluted passageways, which cannot be fabricated satisfactorily using conventional manufacturing techniques. It has also been recognized in some industries that a stereolithographic object or component may be formed or built around another, pre-existing object or component to create a larger product.
Conventionally, stereolithographic apparatus have been used to fabricate freestanding structures. Such structures have been formed directly on a platen or other support system of the stereolithographic fabrication apparatus, which is located within the fabrication tank of the stereolithographic apparatus. As the freestanding structures are fabricated directly on the support system, there is typically no need to precisely and accurately position features of the stereolithographically fabricated structure. As such, conventional stereolithographic apparatus lack machine vision systems for ensuring that structures are fabricated at certain locations.
Moreover, conventional stereolithographic apparatus lack support systems, handling systems, and cleaning equipment which are suitable for use with relatively delicate structures, such as semiconductor substrates and semiconductor devices that have been fabricated thereon.
Accordingly, there is a need for stereolithography apparatus which are configured to form structures on fabrication substrates, such as semiconductor substrates and semiconductor device components and which include systems for accurately positioning the fabricated structures, supporting and handling the fabrication substrates, and cleaning excess and residual material from the fabrication substrates.